Objectives: To determine the efficacy of epidural blood patch (EDBP) for the treatment of post dural puncture headache (PDPH). Methods: We randomised 42 patients who presented with PDPH, lasting 24 h to 1 week, to receive EDBP (n = 19) or conservative treatment (n = 23). The primary end point was any headache at 24 h after the start of treatment. Secondary end points were presence and severity of headache after 1 week. Stratified Mantel-Haenzel analysis was used to adjust for confounders. Results: Two patients refused to participate directly after randomisation and allocation to conservative treatment. They were excluded from the study. At 24 h after the start of treatment, headache was present in 11 (58%) patients allocated to EDBP and in 19 (90%) patients allocated to conservative treatment (RR 0.64, 95% CI 0.43 to 0.96). At day 7, headache was present in three (16%) patients allocated to EDBP and in 18 (86%) allocated to conservative treatment (RR 0.18, 95% CI 0.06 to 0.53). Headache was mild in all three EDBP patients, but in 10 of 18 conservatively treated patients who had not recovered by day 7 it was classified as moderate or severe. Adjustments for confounders did not affect these results. Conclusions: EDBP is an effective treatment for PDPH. It offers complete resolution of symptoms in a large proportion of patients. In the remaining patients, it reduces headache severity and allows them to return to their everyday activities.